Lossy compression have shown great success in recent research[1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}. In this paper, we focus on lossless compression.
The basic idea of a lossless compression algorithm is to represent more likely appeared data with shorter codewords, while less frequent data with longer ones, such that the codeword is shorter than the original data in expectation.
For example, an image with each pixel randomly generated is rarely seen in the real world, while a real picture taken by a camera occurs much more often, so the latter compresses better for almost all image compression algorithms.
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